The survey's panelists, whose comments were submitted anonymously, noted that the Alhambra is faring well because the community that hosts itthe town of Granadahas resisted commercializing its top tourist attraction.

Wrote one panelist: "Redevelopment of the city over the past 20 years has been broadly sympathetic to the ancient Moorish core, and although the number of outlets catering [to the] tourist trade has increased noticeably, the city does retain a coherent Andalusian character."

Even the rural destinations topping the list, such as the remote parks and gateway towns that make up New Zealand's Te Wahipounamu region, benefit when the local community feels it has a stake in the site, the panelists agreed.

Of the coastal destination on New Zealand's South Island, one panelist noted: "There is no issue with local people not protecting it; they are all active protectors. All tourists need reminding that they are entering an exceptional place, that it is a privilege to be there."

Mexico's colonial city of Guanajuato was the fifth on the list and was the most improved destination since the Center for Sustainable Destinations conducted its last survey in 2004.

In spite of development, the city has worked to preserve its local color, the experts said. One panelist noted that the streets have been repaved in recent years in a traditional fashion. Panelists also praised the hotels, which are largely old, rehabilitated buildings in the city center.

Faring Poorly

The bottom scorers highlight the host of problems that some sites have yet to tackle, ranging from environmental damage to political trouble, the experts said.

The Potala Palace in Tibet earned the fourth worst score, because while it remains an architectural gem, the city of Lhasa has lost its cultural integrity as a result of Chinese efforts to eradicate Tibetan culture, the panelists said.

Meanwhile, the Spanish colonial ruins at Portobelo/San Lorenzo in Panama, the second worst scorer, have degraded under the pressures of overbuilding and deforestation in the surrounding national park.

Nepal's Kathmandu Valley came in dead last for the dense air pollution and modern construction that surrounds many ancient temples there.

But Ecuador's Galápagos Islands, which earned the third lowest score, experienced the biggest drop-off of any site since the 2004 survey.

Panelists said that although the Galápagos maintain 95 percent of their native species, invasive species of plants and animals pose a serious threat to the islands.

Johannah Barry, president of the Virginia-based nonprofit Galápagos Conservancy, said new residents in the Galápagos are bringing domestic animals and plants to the fragile island ecosystem.

"Introductions become problematic because the species here have evolved in isolation, and so they don't have a lot of defenses," Barry said.

Likewise, she notes, nonnative insects have hitched rides with tourists on boats to the islands, and many of the bugs have established themselves as a threat to native species.

New efforts to enforce quarantines and inspections of tourist boats are in place, Barry added, but the programs are "not terribly well funded."